1. Field of the invention
The present invention relates to a yarn-threading method and device by which a running yarn can be drawn and held at fast speed and the yarn thus drawn and held can be threaded on high-speed rotating or moving means for feeding or receiving a yarn such as a high-speed rotating godet roller in a spinning process or a high-speed rotating bobbin in a winding process. The rotating or moving means for feeding or receiving a yarn may be reffered to as a winder means hereafter.
2. Description of the prior art
It is well-known that a movable suction gun is available for the purpose of catching a running yarn and threading it on a rotating or a moving means, say, a godet roller, a winder bobbin or a yarn guide. It is also well-known that pressurized air or water is used as a working fluid by which a yarn is drawn into a suction gun.
Lately, with the progress of technology, a high-speed winder that handles a yarn at a rate of 4,500 m/min. has been developed for practical application.
In such a high-speed yarn-handling device a movable suction gun that can thread a yarn on a yarn-handling element with a peripheral speed exceeding 4,500 m/min. such as a godet roller or a winder bobbin should be able to draw the yarn at a speed of not less than 4,500 m/min. and be able to maintain this state of suction continuously.
The yarn-sucking speed available from the conventional movable suction gun, however, is at most 4,000 m/min. and this speed is widely accepted in the industry. Thus, for the introduction of said high-speed winder in the industry the rotating speed of the yarn-handling element has to be slowed down to a speed of less than 4,000 m/min. so that the conventional suction gun can catch the running yarn, and after threading, the high-speed yarn-handling element goes into full operation at regular speed. This may be one mode of threading with the use of the conventional suction gun but in this mode the available high-speed is not fully used and the superior high-speed winder cannot display its full performance. Hence a demand has developed for the development of a movable yarn-threading suction gun with a sucking speed exceeding 4,500 m/min.
As described in detail hereinafter, according to the present invention a liquid (specifically water) is employed as the working fluid of the suction gun. Japanese Utility Model Publication No. SHO51-28424 discloses use of water as the working fluid of a suction gun. In this publication it is stated that the purpose of enhancing the yarn drawing power the liquid pressure may be increased, but the increase of the liquid pressure is not a practical solution, because it will also produce an increased impact on the yarn, thereby breaking the yarn.
By way of checking this point, the present inventors made an experiment in which a suction gun using pressurized water of 80 kg/cm.sup.2 G as the working fluid was used to draw and thread the yarn on a godet roller having a peripheral speed of 4,500 m/min. and a suction gun using pressurized water of 100 kg/cm.sup.2 G as a working fluid was adopted to draw and thread the yarn on a godet roller having a peripheral speed of 5,000 m/min. The threading turned out to be unexpectedly successful without any breaking of the yarn despite the extremely high pressure of the water.